Anon Asks:

When Aegon confirmed the titles of those pledging fealty to him, what does that mean? How does a king confirm the properties of his vassals? Does every king do that when inheriting or just when conquering?

This can get a bit complicated and contradictory, but at least in theory under feudalism titles represent a feudal contract between a vassal and their overlord: so if you’re the Knight of Standfast, for example, you hold that land from House Rowan, who holds it from House Tyrell, who holds it from the King. 

That fiefdom is (in theory) a grant from the liege lord that they can give or revoke technically at will. And even in a situation in which practically speaking a feudal system had moved from the Carolingian model in which fiefdoms were considered a grant for life only and then reverted back to the king to an inheritance model in which fiefdoms were considered to be the rightful property of the heir of the previous lord, there still were a lot of medieval ceremonies that took place when either a vassal or a liege lord died, in order to re-enact the agreement between vassal and overlord.

So what Aegon was doing was writing a bunch of feudal contracts, “giving” the lands in question back to his new vassals in return for their homage and an agreement about what kind of service they would give in return (which would include military service, taxation, etc.). And then when Aegon died and Aenys I was crowned, he would have received the homage of his subjects, and at that ceremony the feudal contract would have been renewed between the new king and his subjects. 

Could the king rewrite those contracts and shift the land around? Sure, we’ve seen plenty of examples of it, from the Brackens and the Blackwoods lobbying the King to choose which of them gets various disputed lands, to Harrenhal handed out as a token of royal favor, to the creation of the New Gift and the founding of Summerhall. But it’s risky, because taking land from some to give to others creates a lot of angry people…just ask Raoul of Cambrai.